Trident nuclear programme

The Trident nuclear programme, also known as the Trident nuclear deterrent, covers the development, procurement and operation of the current generation of United Kingdomnuclear weapons and the means to deliver them.

'Trident' is an operational system of four Vanguard-class submarines armed with Trident II D-5ballistic missiles, able to deliver thermonuclear warheads from multiple independently-targetable re-entry vehicles (MIRVs). It is operated by the Royal Navy and based at Clyde Naval Base on the west coast of Scotland, 25 miles from Glasgow—Scotland's largest city and the UK's third largest city. At least one submarine is always on patrol to provide a continuous at-sea capability. Each one is armed with up to 8 missiles and 40 warheads; their capacity is much larger.[1]

The programme was announced in July 1980 and patrols began in December 1994. Since tactical WE.177 free-fall bombs were decommissioned in 1998, 'Trident' has been the only nuclear weapon system that is operated by the UK. Its stated purpose by the Ministry of Defence is to "deter the most extreme threats to our national security and way of life, which cannot be done by other means".[2] Trident replaced the submarine-based Polaris system, in operation from 1968 until 1996.

A programme for the replacement of the Vanguard-class is under way. On 18 July 2016 the House of Commons voted by a large majority to proceed with building a fleet of Dreadnought-class submarines, to be operational by 2028 (with the current fleet completely phased out by 2032) thereby renewing the Trident system and extending its life until the 2060s.[3]

Following the acceleration of the U.S. Trident II D-5 programme, the existing Polaris Sales Agreement was modified in 1982 to permit the supply of the more advanced missiles.[6] Under the agreement, the UK would lease 65 Trident II D-5 missiles from a larger pool of weapons based at Naval Submarine Base Kings Bay in the United States. The U.S. would maintain and support the missiles and the UK would manufacture its own submarines and warheads to go on the missiles.[7]

The programme was projected to cost £5 billion, including the four submarines, the missiles, new facilities at Coulport and Faslane and a five per cent contribution to Trident II D-5 research and development. The option for a fifth submarine was discussed at the time but later discounted, and the number of missiles leased was later reduced from 65 to 58.[8] Trident's future was secured the following year when the Conservative Party won the 1983 general election, defeating the Labour Party which had pledged to cancel it.[9]

The Vanguard-class submarines were built between 1986 and 1998 by Vickers at Barrow-in-Furness, Cumbria. The first British Trident missile was test-fired from HMS Vanguard on 26 May 1994, and the submarine began its first patrol in December of that year. According to the Royal Navy, at least one submarine has always been on patrol ever since.[10] Trident has been the UK's sole nuclear weapons system since the retirement of the WE.177 tactical nuclear weapon following the 1998 Strategic Defence Review.[11]

The Trident programme was initiated during the Cold War, and its capabilities were designed to deter powerful Warsaw Pact forces. By the time of the first Vanguard patrol in December 1994, the Soviet Union no longer existed, and the government adjusted its nuclear policy in the years to follow.[7]

The final decision on firing the missiles is the responsibility of the prime minister of the United Kingdom. Upon taking office, the prime minister writes four identical letters of last resort, each of which is locked in a safe on board the Vanguard submarines. If contact with the UK is lost, the commanding officer of a submarine has to follow the instructions in the letter if they believe that the United Kingdom has suffered an overwhelming attack. Options include retaliating with nuclear weapons, not retaliating, and putting the submarine under the command of an ally.[12] The exact content of the letters is never disclosed, and they are destroyed without being read upon the election of a new prime minister.

Under the terms of a missile lease arrangement, the United States does not have any veto on the use of British nuclear weapons, which the UK may launch independently.[13]

The Trident system was designed to provide an ongoing independently-controlled deterrent against major threats to the security of the United Kingdom and its allies in the North Atlantic Treaty Organization (NATO), including threats posed by non-nuclear weapons.[4] In the 1980s, the most serious threat to the West was perceived to come from the Soviet Union and its Warsaw Pact allies in Eastern Europe.[7]

To provide an effective deterrent, the Trident system was intended to "pose a potential threat to key aspects of Soviet state power" while being invulnerable to a surprise or pre-emptive nuclear strike. As with Polaris, Trident would be owned and operated by the UK but committed to NATO and targeted in accordance with plans set out by the organisation's Supreme Commander in Europe, who is a senior figure in the United States military. The system would be used to defend the UK only if "supreme national interests" required it.[14]

Trident was deemed necessary in case the Soviet Union threatened to attack Western Europe.[4] Without a credible U.S. umbrella, European leaders would have been susceptible to nuclear blackmail, forcing them into making concessions to the Soviets.[15] It was considered vital that an independent British deterrent could penetrate existing and future Soviet anti-ballistic missile (ABM) capabilities. A powerful ABM system, the ABM-1 Galosh, defended Moscow, and NATO believed the USSR would continue to develop its effectiveness. The deterrent logic required the ability to threaten the destruction of the Soviet capital and other major cities.[7] The expensive Chevaline upgrade to Polaris had been designed to keep pace with the ABM developments, but the full MIRV capabilities of the Trident missiles assured the credibility of the system beyond the 1990s.[4]

NATO military posture was relaxed after the collapse of the USSR in 1991. Trident's missiles were "detargetted" in 1994 ahead of the maiden voyage of the first Vanguard-class SSBN.[16] The warheads are not aimed at specific targets but await coordinates that can be programmed into their computers and fired with several days' notice.[2][7]

Although Trident was designed as a strategic deterrent, the end of the Cold War led the British government to conclude that a sub-strategic – but not tactical – role was required; the 1994 Defence White Paper stated: "We also need the capability to undertake nuclear action on a more limited scale in order to … halt aggression without inevitably triggering strategic nuclear exchanges". A later statement read: "We also intend to exploit the flexibility of Trident to provide the vehicle for both sub-strategic and strategic elements of our deterrent … as an insurance against potential adverse trends in the international situation".[17]

On 19 March 1998, the Defence Secretary, George Robertson, was asked to provide a statement "on the development of a lower-yield variant of the Trident warhead for the sub-strategic role". He replied, "the UK has some flexibility in the choice of yield for the warheads on its Trident missiles".[18]

As of 1998, each submarine carried up to 48 warheads, a number that was reduced to a maximum of 40 warheads split between 8 missiles in 2010.[19]

Trident required the design and construction of four very large submarines, the development, testing and assembly of a new generation of warheads, as well as the construction of new shore facilities. This work began in 1980 and the first patrol took place in late 1994. Submarine production continued until 1998, and it is believed that new warheads are still being assembled at a trickle rate. In addition, the UK government provided five per cent of the costs towards the development of the Trident II D-5 missile.[20][better source needed]

Four Vanguard-class submarines were designed and built at Barrow-in-Furness by Vickers Shipbuilding and Engineering, now BAE Systems Submarine Solutions. The Devonshire Dock Hall was built specially for their construction. The missile compartment is based on the system used on the American Ohio class, although with capacity for only 16 missiles, rather than the 24 on board an Ohio boat. From the outset, Vanguard submarines were designed as nuclear-powered ballistic missile platforms able to accommodate the Trident II D-5. The boats are significantly larger than the Resolution class, and they are some of the largest submarines ever built, only eclipsed by the American Ohio and Russian Typhoon- and Borei-classes. The submarines run a version of Windows XP called Windows for Submarines.[21]

In addition to the missile tubes, the submarines are fitted with four 21-inch (533-mm) torpedo tubes and carry the Spearfish heavyweight torpedo[22] allowing them to engage submerged or surface targets at ranges up to 65 kilometres (40 mi; 35 nmi). Two SSE Mark 10 launchers are also fitted, allowing the boats to deploy Type 2066 and Type 2071 decoys, and a UAP Mark 3 electronic support measures (ESM) intercept system is carried. A 'Core H' reactor is fitted to each of the boats during their long-overhaul refit periods, ensuring that none of the submarines will ever need re-fuelling.[23]

The UK has a stockpile of 160–225 nuclear warheads of variable yields.[25][7] Every year, the Atomic Weapons Establishment (AWE) manufactures new warheads to ensure the safety and longevity of the Trident programme. Old warheads are dismantled and refurbished.[26] Warheads have been assembled at the AWE facilities near Aldermaston and Burghfield, Berkshire, since 1992. They are transported to the armaments depot 720 km (450 miles) away at RNAD Coulport in Scotland by heavily guarded convoys.[27] Between 2000 and 2016 the vehicles were involved in 180 incidents, ranging from delays and diversions because of accidents, protests, or bad weather, to a sudden loss of power in one of the lorries, which halted a convoy and caused a double lane closure and a tailback on the M6 motorway. The incidents have been more frequent in recent years.[28] The convoys often use the motorway through the centre of Glasgow, where an accident leaking radiation could affect hundreds of thousands of people, say the International Campaign to Abolish Nuclear Weapons; the MoD does not foresee this happening.[29]

Under an agreement signed by the United States and the UK in 1958, the UK is allowed to draw inspiration from U.S. warhead designs, but constructing and maintaining warheads for the Trident programme is entirely the responsibility of AWE. The exact number of warheads carried on patrol at any given time is classified information.[7] Each warhead is housed in a cone-shaped re-entry vehicle made in the United States.[30] This shell protects it from the high temperatures experienced upon re-entry into Earth's atmosphere.[31]

The Trident warhead's fusing, arming and firing mechanisms are carefully designed so that it can only detonate in the air.[32]

UGM-133 Trident II D-5 is a submarine-launched ballistic missile built by Lockheed Martin Space Systems in Sunnyvale, California, and deployed with the U.S. Navy and the Royal Navy.[33] The British government contributed five per cent of its development costs under the modified Polaris Sales Agreement. The development contract was issued in October 1983, and the first launch occurred in January 1987. The first submarine launch was attempted by the USS Tennessee in March 1989. This attempt failed because the plume of water following the missile rose to a greater height than expected, resulting in water being in the nozzle when the motor ignited. Once the problem was understood, simple changes were very quickly made, but the problem delayed the entry into service of Trident II until March 1990.[34]

Trident II D-5 was designed to be more sophisticated than its predecessor, Trident I C-4, and has a greater payload capacity. All three stages of the Trident II D-5 are made of graphite epoxy, making the missile much lighter than its predecessor.[35] The first test from a British Vanguard-class submarine took place in 1994. By February 2012, there had been a total of 137 successful test flights conducted by the two navies since 1989. [36] The missile is 13 metres (44 ft) long, weighs 58.5 tons (130,000 lb), has a range of 11,300 kilometres (7,000 mi), a top speed of over 21,600 km/h (13,400 mph) (Mach 17.4) and a CEP accuracy to within "a few feet".[37] It navigates using an inertial guidance system combined with star-sighting, and is not dependent on the American-run Global Positioning System (GPS).[2]

While the theoretical capacity of the four Vanguard-class submarines is 64 missiles and 768 warheads, 58 missiles are leased from the United States. The UK leases the missiles from a general pool, together with the Atlantic squadron of the U.S. Navy Ohio-class SSBNs at King's Bay, Georgia. The pool is 'co-mingled' and missiles are selected at random for loading on to either nation's submarines.[38]

In the 1990s, the total acquisition cost of the Trident programme was £9.8 billion, 38 per cent of which was incurred in the United States. In 2005–06, annual expenditure for the running and capital costs was estimated at between £1.2bn and £1.7bn and was estimated to rise to £2bn to £2.2bn in 2007–08, including Atomic Weapons Establishment costs. Since Trident became operational in 1994, annual expenditure has ranged between 3 and 4.5 per cent of the annual defence budget, and was projected to increase to 5.5 per cent of the defence budget by 2007–08.[39] As of 2009, each missile cost the United States government nearly £16.8 million ($29.1 m) to build.[37]

The Prime Minister's command bunker is located beneath the Ministry of Defence in Whitehall, London

The Trident system is currently made up of 58 leased Trident II D-5 missiles, four Vanguard-class ballistic missile submarines and 160 operationally available nuclear warheads,[40] together with command-and-control and other supporting infrastructure. Each submarine is armed with 8 missiles and a maximum of 40 warheads of variable yields.[2]

The principle of Trident's operation is known as Continuous At-Sea Deterrence (CASD), which means that at least one submarine is always on patrol.[41] Another submarine is usually undergoing maintenance and the remaining two are in port or on training exercises. During a patrol, the submarine is required to remain silent and is allowed to make contact with the United Kingdom only in an emergency. It navigates using mapped contour lines of the ocean floor and patrols a series of planned "boxes" measuring several thousand square miles. A 1,000-metre-long aerial trails on the surface behind the submarine to pick up incoming messages. Intelligence is constantly relayed to the vessel, giving details of shipping movements and potentially hostile aircraft or submarines in the area. Most of the 150 crew never know where they are or where they have been.[12]

Only the prime minister or a designated survivor can authorise the missiles to be fired. These orders would likely be issued from the Pindar command bunker under Whitehall in central London. From there, the order would be relayed to the CTF 345 operations room at the Northwood Headquarters facility in Hertfordshire, the only facility allowed to communicate with the Vanguard commander on patrol. Two personnel are required to authenticate each stage of the process before launching, with the submarine commander only able to activate the firing trigger after two safes have been opened with keys held by the ship's executive and weapons engineering officers.

At the end of the Cold War, the U.S. Navy installed devices on its submarines to prevent rogue commanders from persuading their crews to launch unauthorised nuclear attacks. These devices prevent an attack until a launch code has been sent by the chiefs of staff on behalf of the U.S. president. The Ministry of Defence chose not to install equivalent devices on Vanguard submarines on the grounds that an aggressor might be able to eliminate the British chain of command before a launch order could be sent.[42]

The process by which a Trident submarine commander would determine whether the British government is functioning includes, among other checks, establishing whether BBC Radio 4 continues broadcasting.[43] If the commander has reason to believe that the government has ceased to function, the letter of last resort written and signed by the prime minister would be retrieved from a safe bolted to the control room deck and its instructions followed.

Trident is based at HMNB Clyde on the west coast of Scotland. This comprises two facilities: Faslane Naval Base on Gare Loch near Helensburgh, and an ordnance depot with 16 concrete bunkers set into a hillside at RNAD Coulport on Loch Long, 4 km (2.5 miles) west of Faslane. Faslane was constructed and first used as a base in World War II. This remote location was chosen as the base for nuclear-armed submarines at the height of the Cold War because of its position close to the deep and easily navigable Firth of Clyde. It provides for rapid and stealthy access through the North Channel to the patrolling areas in the North Atlantic, and through the GIUK gap between Iceland and Scotland to the Norwegian Sea. Also based there are Astute-class nuclear-powered submarines, Sandown-class mine detection vessels, and Archer-class patrol vessels of the Faslane Patrol Boat Squadron. RNAD Coulport is used to store the nuclear warheads and has docking facilities where they are loaded onto submarines before going on patrol and unloaded when they return to the base. Repair and refit of the Vanguard-class submarines takes place at HMNB Devonport near Plymouth, Devon.[citation needed]

All major pro-independence Scottish political parties – the Scottish National Party (SNP), Scottish Green Party, Scottish Socialist Party (SSP) and Solidarity – are opposed to the basing of the Trident system at HMNB Clyde close to Glasgow, Scotland's largest city and the UK's third largest city. Some members and ex-members of those parties, such as Tommy Sheridan, have taken part in blockades of the base.[citation needed] For a major House of Commons vote in 2007, the majority of Scottish Members of Parliament (MPs) voted against upgrading the system, while a substantial majority of English MPs, Welsh MPs and Northern Irish MPs voted in favour. The house backed plans to renew the programme by 409 votes to 161.[46]

Several campaign groups are against Trident, including the Campaign for Nuclear Disarmament (CND) and Trident Ploughshares. In 2006, a year-long protest at Trident's base at Faslane, named Faslane 365, aimed to blockade the base every day for a year. By 26 January 2007, 50 groups had taken part in blockades, leading to 474 arrests.

Faslane Peace Camp is permanently sited near Faslane naval base. It has been occupied continuously, in different locations, since 12 June 1982.

The Royal United Services Institute (RUSI), a British defence and security think tank, released a paper in July 2010 assessing "four possible options for maintaining both an effective nuclear deterrent and also reducing costs in light of anticipated budget restrictions."[47] These proposals were motivated by the fact that funding for the Trident renewal programme must now come from the core MoD budget.[48]

The paper outlined four options consistent with the purposes of cost reduction:[49]

Normally-CASD submarine Force: "Under this option, the UK would maintain Trident missiles and submarines, and CASD [Continuous At-Sea Deterrence] would be maintained as normal operating practice. But the MoD would accept an increased risk of short interruptions in CASD in the event of unforeseen, and low-probability, mishaps or accidents."

CASD-capable Submarine force: "Under this option, the attempt to maintain CASD in normal circumstances would be abandoned, and replaced by an assumption that it would only be necessary to have the ability to reconstitute CASD if required, and then to maintain it for a significant (though not indefinite) period...In order to maintain a credible reconstitution capability, it would be necessary to maintain submarine patrols. But these would not necessarily have to be on a continuous basis."

Dual-capable submarine force: "This would maintain the plan to build new submarines, but with only four missile tubes (compared with the twelve currently planned) and with an explicit design mandate that asked designers to allow them also to perform conventional roles...It would not be possible, however, for potential adversaries to detect whether or not a particular boat was nuclear-armed when it went on patrol. Such an arrangement could, in time, combine increased survivability for the nuclear force while also holding out the possibility of further reductions in the size and readiness of the nuclear deterrent."

Non-deployed strategic force: "A more radical option would be to abandon submarine-based nuclear weapons altogether, relying instead on a non-deployed arsenal to provide deterrence of future nuclear attacks...The key to an effective UK nuclear deterrent based on this option would be guaranteed, but not prompt, retaliation." Although concluding that "such an option is probably too radical to be politically acceptable at present...It should not be ruled out as a longer-term option, however, perhaps as part of a multilateral agreement to move to lower states of nuclear readiness."

The paper concludes that "given the opportunity costs for conventional capabilities that current plans for Trident renewal are due to incur over the next decade...there is now a growing case for a re-examination of whether there are less expensive means of pursuing this objective. A key element of such a review is likely to be a reconsideration of the need to maintain a commitment to CASD in strategic circumstances that are now very different from those in which it was first introduced."[49]

The product of an 18-month study led by the Cabinet Office, the 2013 Trident Alternatives Review was aimed at establishing whether or not there exist credible alternatives to the UK's submarine-based Continuous At-Sea Deterrent (CASD) in the context of the wider national debate around Trident. Accordingly, the review analysed a range of combinations, delivery systems, and warhead designs as possible alternatives to the current system in an attempt to test their effectiveness against potential targets as well as to discern their affordability.[50]

The review, however, established that all but one of the alternatives to the UK's current nuclear posture would be more costly. This, the report determined, is due largely to the great amount of time the UK would need to develop effective warheads for cruise missiles, which would necessitate the construction of two additional submarines to "fill the gap" between the expiration of the current fleet and the launch of an alternative cruise missile-based system in approximately 2040.[50][51][better source needed]

The single less costly alternative to like-for-like renewal would entail a reduction from four to three submarines-an alternative which, according to the report, would render the UK more vulnerable to being targeted by an adversary who can act when there is no submarine on patrol.[51][better source needed]

Ultimately, the Trident Alternatives Review came to the conclusion that there exist alternatives to Trident that "would enable the UK to be capable of inflicting significant damage such that most potential adversaries around the world would be deterred", although no alternatives would "offer the same degree of resilience as the current posture". The review asserted that whether or not cruise missile-based systems offer a credible alternative to the current nuclear posture would be contingent upon a political judgement on whether the UK could accept a "significant increase in vulnerability" and a reduction in who it could deter.[50]

The publication of the report was met with a mixed and varied reception from different political parties and Non-governmental organizations (NGOs) in the field of non-proliferation and disarmament. While it was welcomed by David Cameron as having confirmed the necessity of like-for-like replacement of Trident, Liberal Democrat cabinet minister Danny Alexander deemed it a demonstration of the fact there are "credible and viable alternatives to the UK's current approach to nuclear deterrence." NGOs including the British American Security Information Council (BASIC) criticized the report for its limited scope and its failure to engage with a wider array of considerations related to nuclear weapons, including environmental and humanitarian considerations.[51][52][53]

In 2011, the non-proliferation and disarmament think-tank BASIC launched an independent cross-party Commission in order to initiate a deeper national debate on the United Kingdom's nuclear weapons policy and examine questions around the contentious issue of Trident renewal. The Commission operated under the chairmanship of former Labour Secretary of State for Defence, Lord Browne of Ladyton (Des Browne); former Conservative Defence and Foreign Secretary, Sir Malcolm Rifkind; and Sir Menzies Campbell, former leader of the Liberal Democrats and Shadow Foreign Secretary.[54]

After three years of deliberation, the Commission released their final report on 1 July 2014 and suggested, with a number of important caveats, that the UK should retain a nuclear deterrent. Most notably, the conclusion acknowledged the significance of the UK's role in disarmament, asserting that, "it remains crucial that the UK show keen regard for its position within the international community and for the shared responsibility to achieve progress in global nuclear disarmament." [55]

BASIC's interpretation of the report also focused on this point, emphasising that the commissioners "agreed that the health of the global strategic environment, particularly nuclear non-proliferation, is critical to national security and is a central consideration. They talk of the need for Britain to maintain its 'glide path down towards disarmament,' to ensure that the renewal decisions the next government will be taking have consistency with the trajectory set by successive recent governments, and that the UK should continue to be 'at the forefront of the multilateral disarmament process."[56]

The Vanguard-class submarines were built with a 25-year life expectancy, taking them into the 2020s. Trident II D-5 missiles are expected to continue in service until at least 2040 following an upgrade.[57] Initial proposals to replace the submarines were passed by the House of Commons by a majority of 248 on 14 March 2007.[58] In February 2016, BAE Systems began design work on prototypes of the new submarines.[59] A vote in the House of Commons on 18 July 2016 determined that the UK should proceed with construction of the next generation of submarines. The House voted in favour of the replacement with 472 votes in favour to 117 against,[60] extending the programme's life until at least the 2060s.[61]

A December 2006 Ministry of Defencewhite paper, entitled "The Future of the United Kingdom’s Nuclear Deterrent", recommended that the nuclear weapons should be maintained and outlined measures that would do so until the 2040s. It advocated the currently preferred submarine-based system, as it remained the cheapest and most secure deterrence option available. Costs for this option are estimated at £15–20 billion based on:

£0.25 billion to participate in U.S. Trident D5 missile life extension programme.

These 2006/7 prices would equate to about £25bn in out-turn price for the successor submarines; the 2011 Initial Gate report confirmed estimates of £2-3bn each for the warheads and infrastructure.[63] These cost estimates exclude the Vanguard five-year life extension and decommissioning, and it is unclear if new Trident missiles will need to be purchased for the life extension programme.[64] Running costs would be about £1.5 billion per year at 2006 prices.[64] The paper suggested parts of the existing Trident system be refitted to some extent to prolong their lives. However, the relatively short (five years) life extension potential of the Vanguard class meant that a new class of SSBNs should replace it in the early 2020s. The first boat of the new SSBN class would take 17 years to be designed and built, making a five-year life extension of the Vanguard class necessary.[62]

The 2010 Strategic Defence and Security Review concluded that the Successor submarine would have eight operational missiles carrying no more than 40 operational warheads between them. This would allow the UK to reduce its stocks of operational warheads from 160 to 120, and the overall stockpile from no more than 225 to no more than 180.[63] They would be carried in a 12-missile common missile compartment designed in collaboration with the US for their SSBN-X, which could accommodate the current Trident D5 missiles and any replacement missile once the D5 reaches the end of its expected life in the 2040s.[63]

On 14 March 2007, the Labour government won Commons support for the plans to renew the submarine system. The proposals were passed by the House of Commons by a majority of 248.[65] Despite a clarification that the vote was just for the concept stage of the new system, 95 Labour MPs rebelled, and it was only passed with the support of the opposition Conservative Party.[65][66] It was the first time MPs had been given the chance to vote on whether the UK should remain a nuclear power, and the biggest rebellion since the beginning of the 2003 Iraq war.[65]

The Labour government proposed that the final decision to manufacture should be made in 2014.[67] The new 2010 coalition government agreed "that the renewal of Trident should be scrutinised to ensure value for money." Research and development work continued with an 'Initial Gate' procurement decision, but the 'Main Gate' decision to manufacture a replacement was re-scheduled for 2016, after the 2015 General Election.[67] The vote on whether to replace the Vanguard-class submarines with the Successor-class was held on 18 July 2016 in the House of Commons of the United Kingdom; the motion to do so passed with a significant majority[68] extending the programme's life until at least the 2060s. As expected, Jeremy Corbyn and 47 Labour MPs had voted against it; 41 did not vote but 140 Labour votes were cast in favour of the motion.[69]

In April 2015, a YouGov poll found that 38% of people thought that Trident should be replaced in full, 28% wanted to replace it with a cheaper system, 19% though the UK should completely give up its nuclear weapons and 15% didn't know.[70] In September 2015, a Survation poll found that 29% agreed that Trident should be reformed to make it cheaper, 26% that it should be renewed in full, and 18% that it should be scrapped. 27% did not know.[71]

Nuclear weapons are not the nation's biggest issue, with just 2% of people saying that it was nation’s biggest worry in May 2015, compared to 21% in June 1987.[72]

In 2010, two non-representative polls of experts from the Royal Institute of International Affairs (commonly known as Chatham House) and the Royal United Services Institute were conducted. The first found a majority for RUSI of those that think the benefits of Trident outweigh the costs (53%) compared to those that think the costs outweigh the benefits (13%) or are evenly balanced (34%). The Chatham House poll found a minority in favour of Trident replacement (22%), more in favour of replacing with a cheaper system (43%) with 29% saying the UK should not replace Trident at all.[73]

The Dreadnought-class submarine is the official name of the programme to build a new class of submarines which carry the Trident system.[57] The new fleet of submarines will come into operation by 2028 according to some estimates,[74] and certainly by the 2030s.[75] At the time of the Commons vote, there was already some urgency to move ahead because some experts predicted it could take 17 years to develop the new submarine to replace the Vanguard class.[76][77]

The final cost of replacing the Vanguard submarines will not be known until the project has been completed. In October 2015, Reuters claimed it would cost £167 billion over its 30-year lifespan, or £5.56 billion per year; this figure was disputed by the Secretary of State for Defence, Michael Fallon.[78] The MoD puts the cost of building, testing and commissioning the replacement vessels at £31 billion (plus a contingency fund of £10 billion) over 35 years, or about 0.2 per cent of government spending, or 6 per cent of defence spending, every year.[2]Crispin Blunt, Chair of the Foreign Affairs Select Committee, estimated in July 2016 that the programme would cost £179 billion in total over its lifetime.[79]

^Kuenssberg, Laura (19 July 2016). "MPs vote to renew Trident weapons system". BBC News. BBC. Retrieved 19 July 2016. Jeremy Corbyn has been heckled and accused of lying by his own MPs and told he was “defending the countries’ enemies” as he announced he would vote against renewing Trident.